A number of different methods and systems are known in the art for creating depth maps. In the present patent application and in the claims, the term “depth map” refers to a representation of a scene as a two-dimensional matrix of pixels, in which each pixel corresponds to a respective location in the scene and has a respective pixel depth value, indicative of the distance from a certain reference location to the respective scene location. (In other words, the depth map has the form of an image in which pixel values indicate topographical information, rather than brightness and/or color of the objects in the scene.) Depth maps may equivalently be referred to as 3D maps, depth images, or 3D images.
Depth maps may be created by various techniques, such as by detection and processing of an image of an object onto which a pattern is projected. Methods of depth mapping of this sort are described, for example, in POT international Publications WO 2007/043036 A1, WO 2007/105205 and WO 2008/120217, as well as in U.S. Patent Application Publication 2010/0007717, whose disclosures are incorporated herein by reference. Depth maps may alternatively be created by stereoscopic methods or by time-of-flight measurements, as well as by other methods that are known in the art.
Depth maps may be processed in order to segment, identify and localize objects and their components in the scene. Identification of humanoid forms (meaning 3D shapes whose structure resembles that of a human being) in a depth map, and the exact poses of these forms, which may change from frame to frame, may be used as a means for controlling computer applications. For example, PCT International Publication WO 2007/132451, whose disclosure is incorporated herein by reference, describes a computer-implemented method in which a depth map is segmented so as to find a contour of a humanoid body. The contour is processed in order to identify a torso and one or more limbs of the body. An input is generated to control an application program running on a computer by analyzing a disposition of at least one of the identified limbs in the depth map.